What is the CVSS score of CVE-2017-8559?

CVE-2017-8559 has a CVSS 3.0 base score of 6.1 (Medium). CVSS vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.9%.

Is there a patch available for CVE-2017-8559?

Yes, a patch is available for CVE-2017-8559. Update the affected software to the latest version immediately.

Exchange Server CVE-2017-8559

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2017-07-11 secure@microsoft.com

XSS Microsoft Exchange Server

6.1

CVSS 3.0 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-79 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Output encoding, context-aware escaping MITRE ATT&CK 2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 6.1 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required. EPSS exploitation probability: 0.92%.
Exploit ScenarioDerived	A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 0.9% exploitation probability (EPSS)

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AnalysisAI

Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5 allows an elevation of privilege vulnerability due to the way that Exchange. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5 allows an elevation of privilege vulnerability due to the way that Exchange Outlook Web Access (OWA) handles web requests, aka "Microsoft Exchange Cross-Site Scripting Vulnerability". This CVE ID is unique from CVE-2017-8560. Affected products include: Microsoft Exchange Server.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.1 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

DescriptionCVE.org

Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5 allows an elevation of privilege vulnerability due to the way that Exchange Outlook Web Access (OWA) handles web requests, aka "Microsoft Exchange Cross-Site Scripting Vulnerability". This CVE ID is unique from CVE-2017-8560.

Threat Intelligence Overview

EPSS Score

0.9%

Top 24% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 0.9%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +30

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Cross-Site Scripting MEDIUM

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Affected Products (CPE)CVE.org

cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_16:*:*:*:*:*:*

cpe:2.3:a:microsoft:exchange_server:2013:sp1:*:*:*:*:*:*

cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_5:*:*:*:*:*:*

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Same weakness CWE-79 – Cross-site Scripting (XSS)

View all

CVE-2020-3580 MEDIUM POC

6.1

CVE-2013-7389 MEDIUM POC

4.3

CVE-2021-25299 MEDIUM POC

6.1

CVE-2014-2120 MEDIUM

6.1

CVE-2023-40000 HIGH POC

8.3

CVE-2016-8581 MEDIUM POC

6.1

CVE-2013-5223 MEDIUM POC

5.4

CVE-2025-52367 MEDIUM POC

5.4

Same technique XSS

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CVE-2017-9248 CRITICAL POC

9.8

CVE-2013-1710 CRITICAL POC

10.0

CVE-2024-52875 HIGH POC

8.8

References

Advisories & patches

PATCH https://portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2017-8559 REF http://www.securityfocus.com/bid/99448 REF http://www.securitytracker.com/id/1038852

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GitHub PoC

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